Lane departure warning system
In road-transport terminology, a lane departure warning system is a mechanism designed to warn the driver when the vehicle begins to move out of its lane on freeways and arterial roads. These systems are designed to minimize accidents by addressing the main causes of collisions: driver error, distractions and drowsiness. In 2009 the U.S. National Highway Traffic Safety Administration began studying whether to mandate lane departure warning systems and frontal collision warning systems on automobiles.
There are four types of systems:
- Lane departure warning : Systems which warn the driver if the vehicle is leaving its lane with visual, audible, and/or vibration warnings
- Lane keeping assist : Systems which warn the driver and, with no response, automatically take steps to ensure the vehicle stays in its lane
- Lane centering assist : Systems which assist in oversteering, keeping the car centered in the lane, and asking the driver to take over in challenging situations
- Automated lane keeping systems : Designed to follow lane markings with no human driver.
Rationale and method
One of the main causes of single vehicle crashes and frontal crashes is lane departure. The goal of the lateral support systems is to help to avoid such crashes.Without those LSS systems, lane departure can be unintentional; the car drifts towards and across the edge of the lane. The car then reach a potentially dangerous situation. This system does not work when the edge of the lane is not marked by a line.
A lane detection system used behind the lane departure warning system uses the principle of Hough transform and Canny edge detector to detect lane lines from realtime camera images fed from the front-end camera of the automobile. A basic flowchart of how a lane detection algorithm works to help lane departure warning is shown in the figures.
Lane warning/keeping systems are based on:
- Video sensors in the visual domain
- Laser sensors
- Infrared sensors
History
The concept and a working model of this technology was invented and fitted to a Rover SD1 in England by British inventor Nick Parish in 1988. Patent application No 8911571.1 was made in 1989.The first production lane departure warning system in Europe was developed by the United States company Iteris for Mercedes Actros commercial trucks. The system debuted in 2000, and is now available on many new cars, SUVs, and trucks.
In 2002, the Iteris system became available on Freightliner Trucks' North American vehicles. In both these systems, the driver is warned of unintentional lane departures by an audible rumble strip sound generated on the side of the vehicle drifting out of the lane. No warnings are generated if, before crossing the lane, an active turn signal is given by the driver.
2001
began offering a lane-keeping support system on the Cima 450XV Limited sold in Japan.2002
introduced its lane monitoring system on models such as the Caldina and Alphard sold in Japan; this system warns the driver if it appears the vehicle is beginning to drift out of its lane.2003
launched its Lane Keep Assist System on the Inspire. It provides up to 80% of steering torque to keep the car in its lane on the highway. It is also designed to make highway driving less cumbersome, by minimizing the driver's steering input. A camera, mounted at the top of the windshield just above the rear-view mirror, scans the road ahead in a 40-degree radius, picking up the dotted white lines used to divide lane boundaries on the highway. The computer recognizes that the driver is "locked into" a particular lane, monitors how sharp a curve is, and uses factors such as yaw and vehicle speed to calculate the steering input required.2004
In 2004, the first passenger-vehicle system available in North America was jointly developed by Iteris and Valeo for Nissan on the Infiniti FX and the M vehicles. In this system, a camera monitors the lane markings on a roadway. A warning tone is triggered to alert the driver when the vehicle begins to drift over the markings. Also in 2004, Toyota added a lane keeping assist feature to the Crown Majesta which can apply a small counter-steering force to aid in keeping the vehicle in its lane.2005
became the first in Europe to offer LDWS on its 2005 C4 and C5 models, and its C6. This system uses infrared sensors to monitor lane markings on the road surface, and a vibration mechanism in the seat alerts the driver of deviations.2006
introduced a multi-mode lane keeping assist system on the LS 460, which utilizes stereo cameras and more sophisticated object- and pattern-recognition processors. This system can issue an audiovisual warning and also steer the vehicle to hold its lane. It also applies counter-steering torque to help ensure the driver does not over-correct or "saw" the steering wheel while attempting to return the vehicle to its proper lane. If the radar cruise control system is engaged, the Lane Keep function works to help reduce the driver's steering-input burden by providing steering torque; however, the driver must remain active or the system will deactivate.2007
In 2007, Audi began offering its Audi lane assist feature for the first time on the Q7. This system, unlike the Japanese "assist" systems, will not intervene in actual driving; rather, it will vibrate the steering wheel if the vehicle appears to be exiting its lane. The LDW System in Audi is based on a forward-looking video-camera in its visible range, instead of the downward-looking infrared sensors in the Citroën. Also in 2007, Infiniti offered a newer version of its 2004 system, which it called the Lane Departure Prevention system. This feature utilizes the vehicle stability control system to help assist the driver maintain lane position by applying gentle brake pressure on the appropriate wheels.2008
introduced Lane Departure Warning on its 2008 model-year Cadillac STS, DTS, and Buick Lucerne models. The General Motors system warns the driver with an audible tone and a warning indicator on the dashboard. BMW also introduced Lane Departure Warning on the 5 Series and 6 Series, using a vibrating steering wheel to warn the driver of unintended departures. In late 2013 BMW updated the system with Traffic Jam Assistant appearing first on the redesigned BMW X5, this system works below. Volvo introduced the lane departure warning system and the driver alert control on its 2008 model-year S80, the V70, and XC70 executive cars. Volvo's lane departure warning system uses a camera to track road markings and sound an alarm when drivers depart their lane without signaling. The systems used by BMW, Volvo, and General Motors are based on core technology from Mobileye.2009
began offering a Lane Keeping Assist function on the new E-class. This system warns the driver if it appears the vehicle is beginning to leave its lane. Another feature will automatically deactivate and reactivate if it ascertains the driver is intentionally leaving his lane. A newer version will use the braking system to assist in maintaining the vehicle's lane.2010
offered the 2011 Cadenza premium sedan with an optional lane departure warning system in limited markets. This system uses a flashing dashboard icon and emits an audible warning when a white lane marking is being crossed, and emits a louder audible warning when a yellow-line marking is crossed. This system is canceled when a turn signal is operating, or by pressing a deactivation switch on the dashboard; it works by using an optical sensor on both sides of the car.2011
introduces Audi active lane assist.2012
developed a system that detected lane markings, and identified when a vehicle departed from its driving lane without the use of the turn signal.2013
Mercedes began Distronic Plus with Steering Assist and Stop&Go Pilot on the redesigned S-class in 2013.2014
Tesla Model S comes with advanced lane assistance systems with their 2014 release. It was also released with a speed assist feature where the front facing camera reads the traffic speed limits using the technology of computer vision character recognition system, and then conveys it to the car. On roads where traffic signs are absent, it relies on the GPS data. When the car moves away from a lane at above, the system beeps and the steering wheel vibrate, alerting the driver of an unintended lane change. This happens during speed limit non-compliance as well.Fiat is launching its lane keep assist feature based on TRW's lane keeping assist system. This system integrates the lane-detection camera with TRW's electric power-steering system; when an unintended lane departure is detected, the electric power-steering system will introduce a gentle torque that will help guide the driver back toward the center of the lane. Introduced on the Lancia Delta in 2008, this system earned the Italian Automotive Technical Association's Best Automotive Innovation of the Year Award for 2008. Peugeot introduced the same system as Citroën in its new 308.
Lane departure warning systems combine prevention with risk reports in the transportation industry. Viewnyx applies video-based technology to assist fleets in lowering their driving liability costs. By providing safety managers with driver- and fleet-risk assessment reports and tools, it facilitates proactive coaching and training to eliminate high-risk behaviors. The Lookout Solution is used by North American fleets, and there is research on implementing a lane departure warning system via a mobile phone.